The invention relates to improvements in devices for removing liquids from running webs of photographic material. More particularly, the invention relates to improvements in devices which can wipe off liquid, e.g., a layer of liquid, at least from that side of a running web of photographic film or the like which is not coated with photosensitive material.
Published German patent application Ser. No. 20 48 902 discloses a wiping device which can be used in, or in combination with, a developing machine for exposed webs of photographic material. The wiping device includes a flexible rubber lip which urges the running web against the peripheral surface of a rotating roller. The lip contacts and wipes liquid off that side of the running web which is coated with photosensitive material. The other (uncoated) side of the web is supposed to be relieved of liquid as a result of urging the web against the rotating roll. In other words, successive increments of the uncoated side of the running web are pushed against successive increments of the peripheral surface of the rotating roll, i.e., the liquid is supposed to be squeezed off the uncoated side of the web. It has been found that the liquid removing action of the rotating roll at the uncoated side of the running web is unsatisfactory, i.e., excessive quantities of liquid are permitted to be entrained from a first bath (e.g., a developing bath) into a next-following bath (e.g., a fixing bath) of the developing machine.
Attempts to improve the liquid removing action at the uncoated side of a web of photographic material include the provision of a second elastically deformable lip which replaces the rotatable roll. The second lip cooperates with the lip at the coated side of the running web to simultaneously relieve both sides of the running web of moisture which is entrained as the web is caused to advance through and beyond a liquid bath in a developing machine. As a rule, the coated side of a web of photographic material will accept and entrain more liquid than the uncoated side; this is due to the fact that the photosensitive emulsion swells during advancement through a liquid bath and is thus capable of accepting and entraining more liquid than the uncoated side. Therefore, the rear side of the running web is caused to assume a concave shape which results in the establishment of very pronounced pressure between one of the lips and the marginal portions of the web. The pressure is so pronounced that the one lip is notched and/or otherwise deformed and damaged so that it must be replaced after a short period of use. This necessitates a lengthy stoppage of the developing machine with attendant losses in output.